You have a population of 1.9 billion kids or so, according to Ghast. 700 children represents a very, very small portion of that population. Now, certainly, a sample of that size may be used to say something about the population within error, to the point where you can theorise about the population. However, that's only one sample. ONE sample. In statistics, one sample is not hard evidence or proof - it is simply a representation of the population at the particular point in which the sample was taken. You cannot possibly make the sample 100% random, which means in order for the data to mean anything, either a larger sample size proportional to the population size, or more importantly, multiple different samples from all over the place at different times and under different conditions need to be taken.
For example, recently in a laboratory I was testing quality of various thermocouples in aqueous conditions - I took multiple samples both under same and under different conditions and every sample yielded SIGNIFICANTLY different results.
700 people is a perfectly good sample size. 1 sample is not enough samples. Therefore that statistical information is not enough to form any conclusions about the majority of the population. Having said all of this, I didn't actually read the paper mentioned - I'm just going of what the posts were saying - so if I've mistaken something about the data then please feel free to say so.
Just some info from the website:
IQ and Spanking Worldwide
Straus also found a lower national average IQ in nations in which spanking was more prevalent. His analysis indicates the strongest link between corporal punishment and IQ was for those whose parents continued to use corporal punishment even when they were teenagers.
Straus and colleagues in 32 nations used data on corporal punishment experienced by 17,404 university students when they were children.







































